
/*
** a generic input stream interface
** See Copyright Notice in lua.h
*/

#include <string.h>

#define lzio_c

#include "lua.h"

#include "llimits.h"
#include "lmem.h"
#include "lzio.h"

int
luaZ_fill(ZIO * z)
{
  size_t size;
  const char *buff = z->reader(NULL, z->data, &size);
  if (buff == NULL || size == 0)
    return EOZ;
  z->n = size - 1;
  z->p = buff;
  return char2int(*(z->p++));
}

int
luaZ_lookahead(ZIO * z)
{
  if (z->n == 0) {
    int c = luaZ_fill(z);
    if (c == EOZ)
      return c;
    z->n++;
    z->p--;
  }
  return char2int(*z->p);
}

void
luaZ_init(ZIO * z, lua_Chunkreader reader, void *data, const char *name)
{
  z->reader = reader;
  z->data = data;
  z->name = name;
  z->n = 0;
  z->p = NULL;
}

/* --------------------------------------------------------------- read --- */
size_t
luaZ_read(ZIO * z, void *b, size_t n)
{
  while (n) {
    size_t m;
    if (z->n == 0) {
      if (luaZ_fill(z) == EOZ)
        return n;               /* return number of missing bytes */
      else {
        ++z->n;                 /* filbuf removed first byte; put back it */
        --z->p;
      }
    }
    m = (n <= z->n) ? n : z->n; /* min. between n and z->n */
    memcpy(b, z->p, m);
    z->n -= m;
    z->p += m;
    b = (char *)b + m;
    n -= m;
  }
  return 0;
}

/* ------------------------------------------------------------------------ */
char *
luaZ_openspace(lua_State * L, Mbuffer * buff, size_t n)
{
  if (n > buff->buffsize) {
    if (n < LUA_MINBUFFER)
      n = LUA_MINBUFFER;
    luaM_reallocvector(L, buff->buffer, buff->buffsize, n, char);
    buff->buffsize = n;
  }
  return buff->buffer;
}

/*
 * Local Variables:
 * c-basic-offset: 2
 * indent-tabs-mode: nil
 * End:
 */
